Conventionally, for example, resin molded products serving as interior parts for automobiles, in particular, instrument-panels, garnishes, etc., disposed around windows, need to have a high-quality feeling. Such a resin molded product is formed by preparing a molding mold on which a surface treatment referred to as an embossing process is carried out, and by using the molding mold. Thus, on the surface of the resin molded product, a minute pattern of concavo-convex portions referred to as embossing is formed.
The purpose of forming such embossing lies in that by giving delicate shadows or appropriate luster and touch by the hand onto the surface of a resin molded product, a high-quality feeling is provided from a designing point of view. On the other hand, embossing also has practical purposes, such as making a defective external appearance, such as weld lines, irregularities and the like peculiarly occurred on the product surface in the case of an injection molding by using plastic materials, less conspicuous, and also preventing scratches from occurring on the product surface, or making them less conspicuous.
In this case, for example, as described in Patent Document 1, an embossing product molding mold has been disclosed. In the case of forming embossing on an injection molding mold for an embossing product having a complicated concavo-convex shaped pattern, that is, a so-calling satin embossing pattern, on a metal mold surface, the concavo-convex portions, which are formed by carrying out an etching process on a flat metal mold surface without concavo-convex portions, are formed so as to have concavo-convex intervals in a range from 0.3 to 0.5 mm to which a blast projection material is easily put in a blasting process to be described later so as to adjust its ten-point average roughness (Rz) of the concavo-convex portions in a range from 20 to 40 μm, and next, by carrying out a blasting treatment on the concavo-convex surface by using a beads-state blast projection material under conditions of a particle size of 100 to 200 meshes and a compression pneumatic pressure of 0.2 to 0.4 MPa at the time of blasting, corrosion irregularities due to the etching and under-cuts due to corrosion remaining on the surface of embossing concavo-convex portions are evenly adjusted, and as a finishing treatment, by applying a beads-state blast projection treatment with a particle size of 100 to 200 meshes, selected so as to sufficiently enter the embossing concavo-convex intervals and to allow the blasting traces of the blast projection material to be not so fine or so rough, under a compression pneumatic pressure lower than that of the above-mentioned blasting treatment by the beads-state blasting projection material and higher than 0.2 MPa, fine left-overs of the concavo-convex portions remaining in the inside depths of the concave portions of the embossing concavo-convex portions are eliminated and burrs caused by the blasting traces of the beads-state blast projection material itself are flattened so that the smooth surface of embossing concavo-convex portions only having the traces by the beads-state blast projection material is formed; thus, the above-mentioned Patent Document has disclosed an embossing product molding mold capable of producing an embossing product having high luster and high-quality feeling, which makes a defective external appearance, such as weld lines, irregularities and the like, less conspicuous, and also has a superior scratch-resistant property.